Irregular Nuclear Membranes Research Articles

Diagnostic value of qualitative and quantitative variables in thyroid lesions.

Two hundred and thirty-three thyroid lesions were studied by fine needle aspiration (FNA) cytology using standard cytologic criteria available in the literature. These included 114 cases of nodular colloid goitre (NCG), 47 cases of Hashimoto's thyroiditis (HT), 12 follicular adenomas (FAd), five cases of subacute thyroiditis and three cases of thyrotoxicosis among the benign lesions. The malignant lesions seen were 30 cases of papillary carcinoma (PCa), 16 follicular carcinomas (FCa), three cases with double lesions, e.g. papillary carcinoma with coexisting NCG, and three of papillary carcinoma with HT. Emphasis was given to eight qualitative and quantitative (morphometric) variables in these various thyroid lesions. Cell measurements were done using a Visopan Lux projection microscope. The three qualitative variables included type of nuclear membrane (regular/irregular), type of nuclear chromatin and the presence or absence of conspicuous nucleoli. The quantitative variables studied were nuclear diameter, nuclear area, cytoplasmic diameter, cytoplasmic area & N/C ratio. Statistical analysis was performed in order to know whether the standard cytologic criteria used at FNA cytology in the literature (increased cellularity, microfollicles, increased N/C ratio, absence of significant haemosiderin-laden macrophages and scanty colloid) could differentiate a follicular adenoma from a follicular carcinoma. A statistical analysis was also performed to establish the utility of the qualitative and quantitative variables. The results showed that none of the standard cytologic criteria applied could differentiate follicular adenoma from a follicular carcinoma. With regard to qualitative variables, irregularity of nuclear membrane and presence of conspicuous nucleoli were most significant in papillary carcinoma, followed by follicular carcinoma, then by follicular adenoma; these features being hardly evident in nodular colloid goitre and Hashimoto's thyroiditis. A coarse nuclear chromatin was most significant in follicular carcinomas followed by follicular adenomas. It was less obvious in the benign conditions, but more prominent in Hashimoto's thyroiditis compared with a goitre. It was also not obvious in a papillary carcinoma. Of the quantitative variables, all measurements were greatest in PCa > FCa > FAd > NCG = HT. When differentiating follicular adenoma from follicular carcinoma the qualitative variables of significance were the presence or absence of nucleoli, the chromatin pattern and regularity/irregularity of nuclear membrane; the nuclear area was the most important feature among quantitative variables.

Malignant Plasmacytoid Myoepithelioma of the Palate: Histological Observations Compared to Benign Predominant Plasmacytoid Myoepithelial Cells in Pleomorphic Adenoma of the Palate

Predominant benign plasmacytoid myoepithelial cells in pleomorphic adenoma and malignant plasmacytoid myoepithelioma cells were investigated morphologically. The cells of both tumors were plasmacytoid in appearance and sheet-like. Immunohistochemically, they were positive for keratin, vimen-tin, and S-100 protein, and negative for a-smooth muscle ac-tin. In the malignant cells, large nuclei with irregular nuclear membranes and distinct nucleoi and occasional intranuclear inclusions and nuclear grooves were seen. Ultrastructural findings showed that the benign cells were richer in intermediate filaments and had fewer mitochondria. The intranuclear inclusions and nuclear grooves of the malignant cells were caused by invagination of the irregular nuclear membranes. Taken in their entirety, the above light microscopical nuclear findings may be useful as an adjunct for distinguishing malignant from benign plasmacytoid neoplastic myoepithelial cells of the salivary gland.

Intestinal Extramedullary Plasmacytoma Associated with Amyloid Deposition in Three Dogs: An Ultrastructural and Immunoelectron Microscopic Study

Samples from rectal plasmacytoma in three adult dogs that were diagnosed by light microscopy and immunohistochemistry were examined by electron microscopy. The most common cell type had typical plasmacytoid features. A second cell type was a plasmacytoid giant cell with single or multiple eccentric nuclei, irregular nuclear membrane, abundant and dilated rough endoplasmic reticulum, and numerous electron-dense granules. The third cell type was a histiocytic giant cell that intermingled with plasmacytoid cells. All three tumors had abundant amyloid, mainly in the interstitium but also within histiocytic cells and less commonly in plasma cells or plasmacytoid giant cells. Extracellular and intracellular amyloid fibrils and the contents of membrane-bound electron-dense bodies of plasma cells reacted with antibody to /(-light chain of immunoglobulins by immunogold staining.

Atypical Glandular Cells of Undetermined Significance: Diagnostic Accuracy and Interobserver Variability Using Select Cytologic Criteria

Histologic follow-up of patients with the Bethesda system cervical-vaginal diagnosis of atypical glandular cells of undetermined significance (AGUS), "favor endocervical origin", or "not otherwise specified" (NOS) shows a high percentage of clinically significant (neoplastic or preneoplastic) lesions. Using the criteria of atypical single cells, irregular nuclear membranes, and decreased cytoplasm, eight observers retrospectively reclassified 88 AGUS, "favor endocervical", or NOS smears using a probabilistic scheme. Follow-up showed 46 clinically significant and 42 benign lesions. The mean accuracy for all observers and the experienced observers was 65% and 72%, respectively. For the experienced observers, the mean specificity of a "favor clinically significant" category was 72%; the mean sensitivity of a "favor benign" category was 90%. For the less experienced observers, subclassification had poor predictive value. We conclude that experienced observers may use specific criteria to correctly subclassify AGUS lesions, and this may aid in patient management.

Cytology of "significant" breast ductal proliferations.

To determine the usefulness of fine needle aspiration cytology in diagnosing breast ductal proliferations that fall short of invasive cancer (hyperplasia, atypia and in situ carcinoma). This study was a comparison of the cytomorphology and histomorphology of 30 palpable breast lesions in which an initial fine needle aspiration diagnosis of ductal hyperplasia or atypia was based on available criteria. Among six patients, a cytologic diagnosis of mild hyperplasia, based on monolayered cell sheets, was confirmed in five. Fourteen cytologic reports of moderate hyperplasia, based on three-dimensional cell clusters, cell overlap and sublumens, were confirmed in 12. A cytomorphologic diagnosis of atypical ductal hyperplasia was rejected in four of seven patients. Three cases of marked cytologic atypia were diagnosed histopathologically as ductal carcinoma in situ. In breast aspirates, three-dimensional ductal cell clusters, a swirling pattern of growth, sublumens, cell dyscohesion and conspicuous nuclear overlap indicate moderate ductal hyperplasia. Ductal atypia should be diagnosed only on such nuclear features as anisonucleosis, irregular nuclear membranes, clumped chromatin and eosinophilic macronucleoli. Cytologists should highlight those features which are important to diagnose breast proliferations as "significant" from the viewpoint of progressing to invasive cancer and not attempt too fine a classification of these lesions.

Fine needle aspiration biopsy of breast carcinoma in pregnancy and lactation.

To delineate the cytomorphologic features seen in cancer of the breast during pregnancy and lactation, to compare them to the cytomorphologic parameters in benign conditions and to determine the feasibility of differentiating features of malignant breast carcinoma from those of benign breast lesions during pregnancy. The study group consisted of pregnant or lactating women with breast carcinoma and with benign breast lesions who underwent fine needle aspiration (FNA) of the breast lesions. The findings of FNA were reviewed, analyzed, tabulated and correlated with the pathologic diagnosis of the breast biopsies. Eleven patients had malignant cytomorphologic changes, including increased cellularity, multilayering, enlarged and pleomorphic nuclei, single or multiple nucleoli, mitosis and numerous isolated tumor cells. Secretory changes were scanty. The background was foamy and necrotic. FNA of the benign lesions showed a biphasic cell pattern with cohesion; minimal nuclear pleomorphism; single, regular nucleoli; and naked nuclei in a granular background with foamy macrophages. Increased cellularity with nuclear atypia, single cells and a dirty background was seen in benign and malignant conditions. The main cytologic features that differentiate breast carcinoma from benign conditions during pregnancy and lactation are crowding and overlapping of nuclei, dyscohesion and enlarged, pleomorphic nuclei with irregular nuclear membranes, coarse nuclear chromatin and mitoses. Pregnancy-related hyperplastic changes with atypia can potentially result in a false positive diagnosis of carcinoma.

“Osteoclastic” Giant Cell Carcinoma of the Pancreas

Osteoclastic giant cell carcinoma (OGC) is an uncommon variant of ductal carcinoma of the pancreas. It is important to differentiate this variant from other giant cell pancreatic lesions, particularly the more aggressive pleomorphic giant cell carcinoma. Aspiration cytology was performed in a case of OGC. Aspirates of OGC demonstrated three populations of discohesive cells: (1) large, bizarre, pleomorphic malignant giant cells with high nuclear/cytoplasmic ratios, irregular nuclear membranes and coarse chromatin; (2) spindle or small mononucleate cells; and (3) bland, osteoclastlike epithelial giant cells with multiple small, round, central nuclei and prominent nucleoli. Multinucleate giant cells can be seen in pancreatic abscesses, fat necrosis, pseudocysts, tuberculosis, sarcoidosis and fungal infections. When the cells are associated with malignant epithelial cells, the differential diagnosis includes metastatic carcinoma, malignant melanoma, Hodgkin's disease, large cel anaplastic lymphoma, trophoblastic tumor, epithelioid sarcoma, malignant fibrous histiocytoma, angiosarcoma and rhabdomyosarcoma. Immunohistochemical stains, such as vimentin, S-100, leukocyte common antigen, human chorionic gonadotropin, Factor VII Ag, actin and desmin play an important role in differentiating between these lesions.

Atypical Glandular Cells of Undetermined Significance:Cytologic Criteria to Separate Clinically Significant From Benign Lesions

Histologic follow-up of the cervical-vaginal smear diagnosis of atypical glandular cells of undetermined significance (AGUS) shows a broad spectrum of clinically significant (preneoplastic or neoplastic) and benign lesions. There are few statistical studies that have attempted to separate these AGUS categories based on select cytologic criteria. The authors retrospectively reviewed 116 AGUS without concurrent squamous dysplasia smears (66 clinically significant and 50 benign lesions), and used logistic regression analysis to identify the cytologic criteria of irregular nuclear membranes, atypical single cells, and decreased cytoplasm as useful in separating clinically significant from benign lesions. Using contingency tables, these criteria in combination had a sensitivity 29% and a specificity of 94% in the diagnosis of clinically significant lesions. If any single criterion was present, the sensitivity and specificity were 100% and 28%, respectively. In conclusion, by using key cytologic criteria, a percentage of benign AGUS lesions can be separated from clinically significant AGUS lesions.

Predictors of human papilloma virus in patients with keratinization

Given the prevalence of human papilloma virus (HPV) infection, an attempt was made to determine whether certain factors such as keratinization and/or squamous atypia are associated with its development. Review of our gynecologic cytology files from 1989 yielded 1,615 specimens showing parakeratosis and/or hyperkeratosis, without cytologic evidence of HPV. Concomitant diagnoses included no atypia [keratinization only (KO)], inflammatory squamous atypia (ISA), and squamous atypia (SA). Morphologic follow-up including repeat cytology or biopsy was available for 916 cases, 92 (10.0%) of which possessed changes of HPV. For any case with both cytologic and biopsy evidence of HPV, only the biopsy result was tabulated. HPV on follow-up examination was detected in 52 (6.7%) of the 764 cases with KO; in 20 (20.8%) of the 96 cases with keratinization and ISA (KISA); and in 20 (35.7%) of the 56 cases with keratinization and SA (KSA). The definitive diagnosis of HPV was based on previously described features (Gupta, In: Comprehensive Cytopathology, Philadelphia: WB Saunders, 1991:133-140) including nuclear enlargement with nuclear membrane irregularities in combination with sharply demarcated paranuclear cytoplasmic clearing. Affected cells have rounded borders. Binucleated cells are not uncommon. The increasing percentage of HPV from KO to KISA to KSA is not necessarily surprising. However, mathematical analysis revealed statistically significant differences in the development of HPV in each of the 3 groups: KISA vs. KO (P < 0.001), KSA vs. KO (P < 0.001), and KSA vs. KISA (P < 0.05). Therefore, a cytologic diagnosis of keratinization with ISA or especially SA should warrant closer follow-up than that of KO.

AN “ASYMPTOTIC FRACTAL” APPROACH TO THE MORPHOLOGY OF MALIGNANT CELL NUCLEI

To investigate quantitatively nuclear membrane irregularity, 672 nuclei from 10 cases of oral cancer (squamous cell carcinoma) and normal cells from oral mucosa were studied in transmission electron micrographs. The nuclei were photographed at ×1400 magnification and transferred to computer memory (1 pixel=35 nm). The perimeter of the profiles was analysed using the “yardstick method” of fractal dimension estimation, and the log-log plot of ruler size vs. boundary length demonstrated that there exists a significant effect of resolution on length measurement. However, this effect seems to disappear at higher resolutions. As this observation is compatible with the concept of asymptotic fractal, we estimated the parameters c, L and Bm from the asymptotic fractal formula Br=Bm {1+(r/L)c}−1, where Br is the boundary length measured with a ruler of size r, Bm is the maximum boundary for r→0, L is a constant, and c=asymptotic fractal dimension minus topological dimension (D−Dt) for r→∞. Analyses of variance showed c to be significantly higher in the normal than malignant cases (P&lt;0.001), but log(L) and Bm to be significantly higher in the malignant cases (P&lt;0.001). A multivariate linear discrimination analysis on c, log(L) and Bm re-classified 76.6% of the cells correctly (84.8% of the normal and 67.5% of the tumor). Furthermore, this shows that asymptotic fractal analysis applied to nuclear profiles has great potential for shape quantification in diagnosis of oral cancer.

Hyperplasia of type II pneumocytes in acute lung injury. Cytologic findings of sequential bronchoalveolar lavage.

The organizing stage of acute lung injury syndrome is characterized, in part, by a reactive hyperplasia of type II pneumocytes. These cells may be recovered in large numbers and in an excellent state of preservation by bronchoalveolar lavage. It was noted recently that such cells in lavage samples may mimic adenocarcinoma. To examine the dynamics of type II pneumocyte shedding in acute lung injury, we studied 62 bronchoalveolar lavage samples from 38 patients with acute onset of the adult respiratory distress syndrome (median age, 54 years). A single lavage was performed in 25 patients, whereas from two to five studies were performed in 13 individuals. The timing of lavage ranged from 1 to 435 days after the onset of respiratory distress. Type II pneumocytes were present in 12 specimens as follows: 6 of 24 (25%) samples from days 1 to 3, 4 of 9 (44%) samples from days 4 to 10, and 2 of 11 (18%) samples from days 21 to 32. Specimens obtained after day 32 never contained such cells. Cytologically, type II pneumocytes may resemble the cells of acute radiation injury. Alternatively, they may be smaller, with an increased nuclear-cytoplasmic ratio, nuclear membrane irregularities, and prominent nucleoli, thus resembling the cells of adenocarcinoma. They may shed singly or in groups. A spectrum of changes from small cells to large, fully hyperplastic type II cells may be seen. Recognition of the morphologic features of type II pneumocytes and careful clinical correlation usually will suffice to prevent a false diagnosis of malignancy. Sequential lavage provides a means to study pulmonary epithelial changes after lung injury.

Ultrastructural Changes in Rat Colorectal Epithelium and Tumors after Treatment with N-Methyl-N’-Nitro-N-Nitrosoguanidine and Secondary Bile Acids

Transmission electron microscopy (TEM) was used to study ultrastructural changes that accompanied the tumorous transformation of the descending rat colon epithelial cells, following short treatment with a direct carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), with subsequent prolonged treatment with secondary bile acids, lithocholic (LCA) and deoxycholic (DCA), which enhanced tumor formation. Colon epithelial cells after long treatment with bile acids alone were characterized by the presence of an irregular nuclear membrane, ring-shaped rough endoplasmic reticulum (RER), collagen-like tonofilaments and membrane-bound mucous vacuoles. Tumor cells which developed following treatment with MNNG alone were characterized by the irregular shape of the nuclear membrane and, sometimes, by polynuclei, accumulation of large amounts of mitochondria, loss of cell-cell contacts and by endocytosis of the cell membrane. After combined treatment with MNNG and LCA, many mitochondria lost their membranous envelope; in the cytoplasm many collagen-like tonofilaments, ring-shaped RER and many free ribosomes were present. After treatment with MNNG and DCA, many polysomes were found in the cytoplasm. It was apparent that treatment with MNNG alone caused the development of adenocarcinoma-like tumors, while additional treatment with secondary bile acids significantly enhanced these changes, which were accompanied by the development of atypia and anaplasia of epithelial cells, with many irregularities in intracellular organization.

Comparative Effects of Halothane and Isoflurane Anesthesia on the Ultrastructure of Human Hepatic Cells

The effects of halothane and isoflurane on the ultrastructure of the liver cells in adult patients with normal liver—function tests were compared. After induction of anesthesia with thiopental, fentanyl, and pancuronium, 18 patients were randomly divided into three groups of six each. Anesthesia was maintained with droperidol (droperidol group), with halothane (1.7 MAC, halothane group), or with isoflurane (1.7 MAC, isoflurane group). During the surgical procedure, 2 hr after the induction, a liver biopsy was performed in each patient and processed for light and electron micros-copy. All biopsies were normal on light microscopy. On electron microscopy, no mitochondrial abnormalities were found. In all three groups, irregular nuclear membranes, dilation of the rough endoplasmic reticulum, and vesiculation of the smooth endoplasmic reticulum were seen, without any significant differences between the groups. There were significantly more lysosomes in the hepatocytes of patients receiving halothane than in the hepatocytes of patients receiving isoflurane or droperidol. This study shows that halothane can induce ultrastructure abnormalities very early after the beginning of its administration while, under the same conditions, isoflurane does not.

Cytologic Characteristics of Neoplastic and of Regenerating Hepatocytes in Fine, Needle ASPirates of Rat Liver

L-azaserine (l-aza)-induced hepatocellular carcinoma (HCA) and hyperplastic liver lesions were studied in livers from 86 l-aza treated animals and 16 saline controls. Eight additional rats studied 24 or 48 hr after partial hepatectomy and 8 young rats studied after no experimental manipulation served as additional controls for determination of cytologic effects of increased cell turnover. Fine needle aspirates (FNA) were made of all gross liver lesions and of grossly normal liver; H&E stained sections of liver surrounding each needle track were made. The FNA were fixed in 95% ethanol, stained with a routine Papanicolaou stain, randomized, and evaluated using 18 cytologic features. They were diagnosed without knowledge of the histologic diagnosis or treatment group. Features were analyzed with discriminant function analysis to determine their relative importance in making the diagnosis. FNA proved to be an accurate method for diagnosis of hepatocellular lesions in laboratory animals. The cytologic features of greatest usefulness in establishing the diagnosis were cord pattern, chromatin pattern, nucleolar size and nuclear membrane irregularity. FNA could provide a useful experimental technique for following evolving lesions serially and for identifying subgroups within hyperplastic nodules.

Enhancement of DMN-induced kidney tumors by 1,2-dichlorovinylcysteine in Swiss-Webster mice.

1,2-Dichlorovinylcysteine (DCVC) is known to cause enlarged nuclei in renal proximal tubule epithelium. This study further characterized the cellular changes induced by DCVC. Also a preliminary investigation of the initiator and promoter potential of DCVC was conducted. When given for 4 weeks in drinking water to Swiss-Webster mice, DCVC (50 or 100 micrograms/ml) caused a progressive change in renal epithelia which was persistent at 23 weeks. Enlarged nuclei with uneven chromatin dispersal, multiple nucleoli, and irregular nuclear membranes resided in enlarged, abnormally-shaped cells. These changes were resolved by week 50. Mice initiated with dimethylnitrosamine developed renal tumors by week 27. Mice fed DCVC (10 or 50 micrograms/ml) for 14 weeks following dimethylnitrosamine initiation, had a slightly higher tumor incidence, a higher incidence of invasive tumors, and had multiple renal tumors unlike animals given dimethylnitrosamine alone.

Clinical, histochemical, and ultrastructural correlation in septal endomyocardial biopsies from chronic chagasic patients: Detection of early myocardial damage

In order to recognize early signs of myocardial damage, histologic, histochemical, and ultrastructural studies were performed on septal endomyocardial biopsy tissue obtained from 79 chronic chagasic patients and from 18 patients with atypical chest pain (control group). Abnormal biopsy findings were recognized in 9 of 16 (60%) chagasic patients with no clinical evidence of myocardial damage. In cases of segmental asynergy only, biopsies were abnormal in 18 of 19 patients. When signs of advanced myocardial damage were evidenced by clinical examination or ECGs, all biopsies were abnormal. Mitochondrial, nuclear, and cell membrane irregularities were consistent findings. A peculiar dilatation and filling of the T tubule system with a glycoprotein-like substance and a remarkable increase in monoamine oxidase activity were observed early in the disease and progressed in magnitude and frequency as myocardial damage became more evident by other diagnostic methods. Septal endomyocardial biopsy is a sensitive method for detection of early myocardial damage in chronic chagasic patients. Based on these findings, a modification of the currently used classification is proposed.

Prostatic aspirates a cytomorphologic analysis with emphasis on well‐differentiated carcinoma

In this retrospective evaluation of 72 cases of fine needle aspiration biopsy of the prostate, 25 aspirates from well-differentiated carcinoma were compared with 27 aspirates from benign prostatic enlargement and 20 aspirates from moderately to poorly differentiated carcinoma. Each case was examined by a single observer (V.K.) for multiple parameters including cellularity, dyshesion, nuclear membrane irregularity, anisonucleosis, macronucleoli (major criteria of malignancy), cell and nuclear enlargement, and altered nuclear/cytoplasmic ratio. Cellularity was the most significant indicator, but all major and minor criteria of malignancy were consistently important for distinguishing well-differentiated carcinoma from benign lesions. Systematic use of these meaningful standards enhances diagnostic sensitivity.

Long-term study of liver damage following subcutaneous injection of airborne particle extracts and polycyclic aromatic hydrocarbon fractions.

Female NMRI mice aged 9-12 weeks were each given a single subcutaneous injection of 0.5 ml of a suspension containing either the total extracts or the polycyclic aromatic hydrocarbon (PAH) fraction of airborne particles. Both the total extracts and PAH fractions contain 3 microgram benzopyrene. After about 15 months the livers were removed from the animals, which had by that time developed tumors at the injection site, and were subjected to electron-microscopical study. The essential alterations were observed in the nucleoli and the cell nuclei, which had greatly proliferated and exhibited irregular nuclear membranes. Advanced fibrosis was observed in central liver specimens of all groups. Marked alterations were also observed in the mitochondria and the mitochondrial cristae as well as in the bile canaliculi, Intracytoplasmic glycogen usually occurred densely clustered along the periphery of the cell. It may be concluded from the observations that both the total extract of atmospheric suspended particulate matter and the PAH fraction cause hematogenic damage to the liver following subcutaneous injection, a finding which cannot be interpreted as metastatic carcinoma.

Cytological Findings of Neuroblastoma and Wilms' Tumor

The cytological examination of touch smears prepared from 3 patients with neuroblastoma, 2 with Wilms'tumor and 2 with pulmonary small cell carcinoma, were performed. The purpose of this paper is to know whether cytologically differential diagnosis of malignat tumors in childhood is possible or not. The specimens were stained by Papanicolaou's, May-Giemsa's and Giemsa's method. The findings of touch semears were compared with those of histological and electromicroscopic sections.Characteristics of neuroblastoma were as follows:1) Tumor cells were seen in a single and irregular clusters.A few rossete formation were found.2) Neuroblastoma cells were round or oval, almost naked, 8-22μ in size.3) Nuclei of neuroblastoma cells were composed of highly increased chromatin with fine granular structure, and some of them had small nucleoli.4) Electronic microscopy revealed that immature tumor cells were scanty cytoplasma with small numbers of organellas and moderately mature cells were abundant with many.Feature of these cells was characterized by the presence of numerous cytoplasmic processes excluding into the intercellular space. They contained numerous organellas and some neurosecretory granules.Wilms' tumor was as follows:1) Epithelial cell clusters and sarcomatous spindleshaped cells in irregularly-overlapping clusters were found.2) The nuclei of tumor cells were oval in shape, 9-22μ in size, and were composed of moderately increased chromatin with fine reticular pattern.3) Under electron microscopy, the cytoplasma was fround abundant with many organellas and the desmosome and pseudolumen between adjacent cells were found.Pulmonary small cell carcinoma was followings:1) The cytological findings were resemble to neuroblastoma in the point of the cell-arrangement and naked nucleus.2) Tumor cells were 9-19μ in size and nuclei were composed of severe increased chromatin with irregular nuclear membrane. But a quantity of chromatin among the tumor cells was different in Papanicolaous'stain.By the cytological findings described above, it was possible to distinguish neuroblastoma from Wilms'tumor and pulmonary small cell carcinoma in diagnostic cytology.

An electron microscope study of motoneurones and interneurones in the cat abducens nucleus identified by retrograde intraaxonal transport of horseradish peroxidase

AbstractAbducens motoneurones innervating the lateral rectus muscle and abducens interneurones projecting to the oculomotor nucleus have been studied in the cat by light and electron microscopy following labelling with horseradish peroxidase. Motoneurones ranged from 15–60 μm in diameter and typically contained circular nuclei with smooth or slightly irregular nuclear membranes and extensive cisternae of granular endoplasmic reticulum. Interneurones ranged from 25–50 μm in diameter and comprised two cytologically distinct cell types. One type was fusiform in profile and contained nuclei with fluted or deeply invaginated nuclear membranes and poorly developed granular endoplasmic reticulum. The other interneurone type resembled the motoneurones cytologically, having multipolar or circular profiles, smooth or slightly irregular nuclear membranes, and well developed cisternae of granular endoplasmic reticulum.The densities with which boutons were distributed on the somata of motoneurones and interneurones were similar, as were the ratios of boutons containing spheroidal or flattened synaptic vesicles. Motoneurones varied significantly in the density with which boutons were distributed on their somata, and had greater densities on their dendrites than on their somata. Density was, furthermore, not correlated with motoneurone soma diameter. The proportion of spheroidal or flattened vesicle boutons on the somata of motoneurones was almost equal, with comparatively little variation between individual motoneurones. Motoneurone dendrites, however, with the exception of lateral dendrites, had a relatively higher proportion of boutons containing spheroidal synaptic vesicles. The lateral dendrites, which extend toward the medial vestibular nucleus, a known source of inhibitory afferents to the abducens motoneurones, had a higher proportion of boutons containing flattened vesicles.The results indicate that abducens motoneurones and interneurones cannot be distinguished by any simple morphological criteria. The somadendritic distribution of boutons on motoneurones appears to be governed by certain broad rules.